Unauthorized increase in account limit

On 15 March, I received an SMS from MTN saying I have reached 90%of my R4k limit.I called MTN to query. The agent explained that there was hi data usage the Fri before.At the time I was unaware of the data usage & requested an investigation.The agent explained that it can only be investigated when the statement closed on the 20th.At the time I didn't realise that I will only be billed the following month.So I explained that I need to know sooner before I pay.Instead of explaining the agent tells me there's no other way around it. So I asked to speak to a manager & he refused.Instead he says that I am not listening to him. Is this the way MTN speaks to their 'valued' clients?<br> In the end i speak to his manager.I think her name was Belinda.She explains that I will only be billed the following month.I then realise that I used a WiFi network on Fri to download and it was not meant to use the MTN network.However,I queried why there is a R4k limit. Belinda initally says that I would NOT have selected the limit. i then queried when I was informed of it.Berlinda explaisn that due to an error in 2011 it needed to be raised.Berlinda could not confirm if I agreed to this going forward